Milling Lighting Gobos

Introduction: Milling Lighting Gobos

Hi! We're Other Machine Co. We develop and manufacture the Othermill, a tiny desktop mill for making things like PCBs, stamps, food molds, and other useful things.

Lighting gobos are used in high-intensity spotlights to give shape to light. A gobo is a fun tool that’s great for everything from pro theater to kindergarten birthday parties.

Basic gobos are made by cutting a shape or image out of thin metal to make designs on walls or screens. “Gobo” is a lighting term that comes from “goes between optics.” We thought a gobo would be a fun and simple way to show off what the Othermill can do.

We made our gobo specifically for an old Ikea Isbrytare spot lamp we had lying around, but you can make these for any gobo holder up to 5"x4". We designed ours in EAGLE for ease of use with Otherplan, our custom motion-control software.

Step 2: Prep Your Material

For a proof of concept, and because aluminum is expensive, we used an empty beverage can as our material. (Asian drink brands tend to work better for this, as the aluminum is more rigid. Seek out your favorite ethnic grocery and give them a try.)

If you need this to be a bit less punk rock and slightly more precise, go ahead and spring for brand-new flat aluminum stock. You can find it at most craft stores or hobby websites. The aluminum we used was about .0125" (about .3mm) thick.

If you're using a can, cut the top and bottom off with the utility scissors. Cut down the side, unroll the aluminum, and flatten the can as much as possible. The can will also naturally flatten out as you continue through the steps, so there's no need to get it absolutely perfect here.

Step 3: Trim, Measure, and Scrub

Tidy up the edges of your can with the utility shears. By now you've realized the edges are sharp. Be careful!

Measure out the size of the gobo you want to make. It's a good idea to start with material slightly bigger than your final product. In this case, our lamp had a holder that fit a 2"x2" circle, so we cut a 3" x 3" square for a workpiece.

With the steel wool or sandpaper, scrub off the lining and paint on the can. This will ensure that when the gobo is exposed to the hot lamp in the lighting element, nothing will burn off or cause fumes.

Step 4: Load Your Materials

A sacrificial layer is the term used in machining to describe something that goes between the workpiece (the part you're making) and the bed of the machine. In this case, because we're cutting such thin material, we're using machining wax underneath our aluminum so that the tool in the mill doesn't chew up the machine bed when it cuts all the way through. If you don't have machining wax, you can use a piece of fine-grained softer wood.

Secure the aluminum to the sacrificial layer using double-sided tape. Press down firmly to make it as flat as possible. Alternately, you can use a few beads of hot glue and press firmly. Take care not to use too much adhesive, as it could gum up the tool in the mill.

In Otherplan, choose Machine > Load/Unload Material. The machine bed will come forward so you can set your material on it. Secure the bottom of the sacrificial layer to the bed of the machine with a drop or two of hot glue along each edge.

Step 5: Import the File Into Otherplan

In Otherplan, import the file by clicking "Import Files" in the Plans panel.

You can also make your own file in any shape you like. EAGLE worked well for us, although it has its artistic limitations.

If you're already familiar with other CAM software, you could convert a custom image to an Otherplan-supported file. Otherplan supports EAGLE .brd files, Gerber files, vector graphics (.svg), and G-code, with more to come.

NOTE: If you do create your own file (and we hope you do!), the image has to be a certain ratio to the material in order for it to show up properly in the lighting element. For example, in our 2"x2" circular gobo, the cut-out size that worked was roughly .75". Any larger and it won’t project properly.

Step 6: Set Your File Origins in Otherplan

Once you've imported the file, it should appear in a panel in Otherplan. In that panel, edit the origin so that the x-axis is 10mm, y is 10mm, and z is the thickness of your sacrificial layer. Press return. The plan should update and move onscreen so it’s rendered in the middle of the material on the bed.

Setting the z-axis to the thickness of the sacrificial layer will make the file look like it's floating in space in the Otherplan window, but it means that the machine will only cut through the gobo aluminum, not the whole sacrificial layer.

Step 11: Finish Up and Enjoy Your Gobo

If everything has gone smoothly, the machine will re-home when its finished, and you'll have a gobo!

Remove it from the machine by choosing Machine > Unload Material. Remove any cruft or uneven edges with a craft file or a bit of sandpaper. Be careful, though, as small metal flanges can be sharp and delicate.

Now all that's left is to put your new gobo in your lighting element and shine it somewhere!

As always, feel free to send your questions or comment to us at support@othermachine.co. And if you make your own custom gobo, be sure to share it with us!

Comments

It may seem odd in a Windows-dominated machining world to have a product that only works on a Mac at the outset, but the choices for machining tools that work natively on the operating system are limited in OS X. As we want to make things accessible for all users, including designers, artists, and others who tend to work with Macs, we thought we would start with a Mac-native approach and branch out.

We are currently developing Otherplan for Windows, but we don't have a timeline for it yet. If you'd like to sign up for our newsletter on our website, you'll get all the latest, including when Windows support is released.

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